This invention relates to an alloy resistant to corrosion and wear at an elevated temperature which is used for making of a cast rotatory cylinder, that is, a kind of spinner, applied to the manufacture of glass fiber by ejecting hot molten glass with an accelerated centrifugal force through fine orifices bored in the lateral wall of the rotatory cylinder. A structure of the rotatory spinner is shown in U.S. Pat. No. 4,392,878.
The rotatory cylinder applied to the manufacture of glass fiber with a centrifugal force is itself highly heated in the air atmosphere and is rotated at such a high speed as 2,000 r.p.m. Further, molten glass flows out quickly through fine orifices bored in the lateral wall of the rotatory cylinder. Therefore, the following characteristics are demanded of an alloy constituting the rotatory cylinder.
1. The alloy should have such an elevated temperature mechanical strength as can withstand the centrifugal force resulting from the high speed rotation.
2. The alloy should fully withstand the frictional wear caused by the quick flow of molten glass through the orifices.
3. The alloy should have sufficient oxidation resistance at elevated temperatures.
4. The alloy should be fully resistant to corrosion with respect to the molten glass.
5. An oxide layer unavoidably deposited on the surface of alloy should have prominent corrosion resistance with respect to the molten glass.
The known alloys constituting the rotatory cylinder include a Ni-Cr alloy containing one or both of Co and W (set forth, for example, in U.S. Pat. Nos. 3,010,201, 3,318,694 and 3,806,338); a Co-Cr alloy containing one or both of W and Ni (disclosed, for example, in U.S. Pat. No. 3,933,484); and a Fe-Ni-Cr alloy (for example, SUS 310).
Among the above-listed alloys, however, SUS 310 used as a material of the rotatory cylinder alloy has so extremely a short life as deserves no consideration at all. The above-mentioned Ni-Cr alloy containing Co and/or W and Co-Cr alloy containing W and/or Ni involves a large amount of expensive Co or W in order to precede particularly elevated temperature mechanical strength from among the various characteristics demanded of the alloy. Therefore, such alloy has such a drawback as its manufacturing cost being increased, and the alloy itself and the oxide layer deposited thereon losing corrosion resistance with respect to the molten glass. These result in a decline in the durability of the rotatory cylinder.